the fruit on the thornless bramble bush is so bitter I am unable to eat any of them. Apart from making pies or jam etc is there anything I can do to make sure the fruit, as in other years, is sweet and pleasant to eat "raw"

The bush is on the colder side of the garden but other years has always been very successful in sweet abundant fruits. There is nothing around it that it could be cross pollenated with, holly bush is the nearest bush.

Answers

If it has been a cold wet summer where you live you have your answer. Fruit only ripens properly in sunshine. I would think you are down to making jam and freezing them for pies and crumbles this year.